Cresswell A G, Thorstensson A
Ergonomics. 1989 Oct;32(10):1237-46. doi: 10.1080/00140138908966893.
A series of standardized tasks, isometric trunk flexion and extension and maximal Valsalva manoeuvres, were used to evaluate the role of the abdominal musculature in developing an increased intra-abdominal pressure (IAP). Seven male subjects were measured for IAP, myoelectric activity of rectus abdominis (RA), obliquus externus and internus (OE and OI respectively), erector spinae (ES) and isometric trunk torque. IAPs in all experimental conditions were markedly greater than those that occurred while relaxed. In isometric trunk flexion, IAPs were increased with accompanying high levels of activity from the abdominal muscles. In contrast, little activity from the abdominal muscles occurred during isometric trunk extension, although levels of IAP were similar to those found in the isometric flexion condition. With maximal voluntary pressurization (Valsalva manoeuvre) slightly higher levels of IAP than those found in torque conditions were recorded, this pressure being produced with abdominal activities (OE and OI) less than one fourth their recorded maximum. When isometric torque tasks were added to the Valsalva manoeuvre, patterns of muscle activity (RA, OE, OI and ES) were significantly altered. For Valsalva with isometric trunk extension, activity from OE and OI was reduced while IAPs remained fairly constant. These findings indicate that in tasks where an IAP extension moment is warranted, abdominal pressure can be increased without the development of a large counter-moment produced by the dual action of the trunk flexors. Activation of other muscles such as the diaphragm and transversus abdominis is suggested as helping provide control over the level of IAP during controlled trunk tasks.
一系列标准化任务，即等长躯干屈伸和最大瓦尔萨尔瓦动作，被用于评估腹部肌肉组织在增加腹内压（IAP）方面的作用。对七名男性受试者测量了腹内压、腹直肌（RA）、腹外斜肌和腹内斜肌（分别为OE和OI）、竖脊肌（ES）的肌电活动以及等长躯干扭矩。所有实验条件下的腹内压均明显高于放松时的腹内压。在等长躯干屈曲时，腹内压随着腹部肌肉高水平的活动而增加。相比之下，在等长躯干伸展过程中，腹部肌肉活动很少，尽管腹内压水平与等长屈曲条件下的相似。在最大自主加压（瓦尔萨尔瓦动作）时，记录到的腹内压水平略高于扭矩条件下的水平，这种压力是由腹部活动（OE和OI）产生的，其活动量不到记录最大值的四分之一。当在瓦尔萨尔瓦动作中添加等长扭矩任务时，肌肉活动模式（RA、OE、OI和ES）发生了显著改变。对于等长躯干伸展的瓦尔萨尔瓦动作，OE和OI的活动减少，而腹内压保持相当恒定。这些发现表明，在需要腹内压伸展力矩的任务中，可以增加腹部压力，而不会因躯干屈肌的双重作用产生大的反向力矩。建议激活其他肌肉，如膈肌和腹横肌，以帮助在受控躯干任务中控制腹内压水平。
